A new series of macrocyclic polyether derivaties will be synthesized and their metal cation binding properties will be measured before and after one-electron reductions. All compounds in this series contain functional groups attached to the polyether macroring which are susceptible to one and/or two electron reduction. Preliminary results show that the anionic functional groups participate strongly in the metal cation binding process together with the macroring donor atoms. In some of the studied cases the binding constants increase by a factor of 25,000 after electron transfer is effected. The proposed systems have been designed to optimize the stability of the anionic species as well as to afford extra flexibility by providing the possibility of one or two-electron reduction. This added flexibility sets the basis for a "tunable" molecular switch, which can be turned-on to complex specific cations (an element of selectivity). The binding characteristics will be determined using electrochemical techniques, ESR spectroscopy, and NMR spectroscopy. Transport kinetics through synthetic membrance will be used to study selectivity as well as transport efficiencies as a function of applied voltage and current. Attempt will be made to isolate the alkali metal-macrocyclic polyether complexes as solids.